LinuxQuestions.org - What does your shell prompt look like?

A couple of years ago I posted a script that I created that will truncate the $PWD and format it for use in the prompt.

Since then I've modified it some more and converted it into a function, and I use it like this:

Code:



#Set some color escape sequences.

#================================#

export RESET='\e[0m' #disable any colors



# Regular colors.

export BLACK='\e[0;30m' RED='\e[0;31m' GREEN='\e[0;32m' YELLOW='\e[0;33m'

export BLUE='\e[0;34m' MAGENTA='\e[0;35m' CYAN='\e[0;36m' WHITE='\e[0;37m'



# Bolded colors.

export BBLACK='\e[1;30m' BRED='\e[1;31m' BGREEN='\e[1;32m' BYELLOW='\e[1;33m'

export BBLUE='\e[1;34m' BMAGENTA='\e[1;35m' BCYAN='\e[1;36m' BWHITE='\e[1;37m'



#=========================#

# Command prompt settings #

#=========================#



# Function for setting a nice variable-length shell prompt.

#==========================================================#

function variprompt {



# This function takes the $PWD or other input string and truncates it to a

# set percentage of the terminal width.  It's designed for use in the bash

# $PS1 prompt to keep it from taking up too much space.  There may be minor

# variations in the actual length due to rounding in the arithmetic.



# Set the desired width of the string below as the percentage of the total

# terminal width.  Remember that any other parts you add to the prompt (such as

# username) will take up additional space.  Also be aware that this script is

# designed for reasonable numbers, and may act in unpredictable ways if the

# target and/or terminal width are very small.  Target values under 25 are not

# recommended.  Will use $1 if it exists, or defaults to the set value.



TARGETPCT=${1:-40}



# Get the current directory or input string.  This will $2 if it exists, or else

# It will default to $PWD.  In addition, if the string includes the $HOME

# directory, it will truncate it to "~".  Simply comment out the second line if

# this behavior is unwanted and you always want the full path.



CURRENTDIR="${2:-$PWD}"

CURRENTDIR="${CURRENTDIR/#$HOME/~}"



# Be sure that the shopt option "checkwinsize" is enabled, so that the curent

# shell width (COLUMNS) is available to this function.  If the $COLUMNS variable

# is unavailable, the following line will set it to 100 instead.  Alternatively,

# you can manually set this variable to a fixed value of 100, and the output

# will always be TARGETPCT columns wide.



COLUMNS=${COLUMNS:-100}



# Determine the number of characters in the input string and calculate

# the total target length and the sizes of the starting and ending segments.



CURRENTLENGTH="${#CURRENTDIR}"

TARGETLENGTH="$(( COLUMNS * TARGETPCT / 100 ))"

FIRSTPART="$(( TARGETLENGTH / 3 - 3 ))"

LASTPART="$(( CURRENTLENGTH - ( TARGETLENGTH * 2/3 ) ))"



# Finally we compare the current length of the prompt to the target length

# and print the appropriate output string.



if (( CURRENTLENGTH <= TARGETLENGTH )); then



    # No modifications are necessary. Print the unmodified string.

    echo "$CURRENTDIR"



else



    # Very small target or column values can make "FIRSTPART" zero or less.

    # So test it to avoid throwing out an error, and set it to display only the

    # first two characters of the string in such situations. Otherwise, print

    # the desired truncated string.



    if (( FIRSTPART > 1 )); then

          echo "${CURRENTDIR:0:$FIRSTPART}...${CURRENTDIR:$LASTPART}"

    else

          echo "${CURRENTDIR:0:2}...${CURRENTDIR:$LASTPART}"

    fi



fi



}



# End function.

#==============#



# Set the prompt.

#================#



# Set checkwinsize option, it's needed to ensure COLUMNS variable is read properly.



shopt -s checkwinsize



# Pattern to set the window title portion of the prompt, if in an xterm.

# The formatting pattern goes between '\e]0;' and '\a' (\a = \007).



if [[ "$TERM" =~ xterm ]]; then

    XTITLE='\e]0;\u:$(variprompt 55 2>/dev/null)\a'

else

    unset XTITLE

fi



# Define PS1 for root and regular users.  Must unquote all the variables.

# Escape sequences must be enclosed in \[ and \] brackets.



if (( UID == 0 )); then

    export PS1='\['${XTITLE}$BRED'\]\u:[\['$MAGENTA'\]$(variprompt 2>/dev/null)\['$BRED'\]]##\['$RESET'\] '

else

    export PS1='\['${XTITLE}$BGREEN'\]\u:[\['$BBLUE'\]$(variprompt 2>/dev/null)\['$BGREEN'\]]$\['$RESET'\] '

fi

Yeah, it seems quite long, but it's mostly comments. :)
The result looks something like this:

Code:



david:[~]$ cd /mnt/musicdir/western_artists/Beatles--Albums/08_Sgt_Peppers_Lonely_Hearts_Club_Band/

david:[/mnt/musicdi...ppers_Lonely_Hearts_Club_Band]$

...but in color. Note also how the window title string can be set to a different length from the prompt itself.